Hose couplings in which either the nipple is to be internally expanded or an external sleeve member is to be reduced in its external diametric dimension within the area of overlap with the hose are known as such. The U.S. Pat. No. 1,786,489 to Hopkins, U.S. Pat. No. 1,825,005 to Loughead, U.S. Pat. No. 2,216,839 to Hoffman, U.S. Pat. No. 2,377,010 to Howard and U.S. Pat. No. 2,595,900 to Soos are representative of such prior art. Additionally, couplings are known in the prior art which propose both internal expansion of the nipple and external compression of the sleeve member, as for example in U.S. Pat. No. 2,399,790 to Conroy and U.S. Pat. No. 2,865,094 to Press. However all of these prior art couplings entail certain disadvantages which lessen their likelihood for successful use in high pressure applications. For example, sharp-edged teeth on the outside of the nipple or sharp-edged teeth on the inside of the sleeve member are likely to cause damage to the hose which seriously jeopardizes the holding ability. Additionally, in many instances the structural details of the couplings involve high manufacturing expenditures and complicated assembly and installation operations.
The aforementioned U.S. Pat. No. 2,399,790 to Conroy describes a method for permanently attaching hose couplings in which internal expansion of the nipple is initially commenced followed by reduction of the diameter of the outer shell. However, in this patent the outer shell is integral with the head and with the externally threaded end so that the stem or insert has to be either threadably connected with the head or held in place by a flanged arrangement resting on the shoulder of the head of the coupling. This means that prior to attaching the hose coupling of Conroy, the latter must be preassembled. Additionally, the ram cap directly engages with the head integral with the shell of the coupling so that the threaded, respectively, flanged connection between the insert and the coupling is likely to be subjected to large stresses.